Wireless networks follow one of two basic structures, fixed router based in which a backbone of fixed routers communicates with wireless nodes, and mobile router based in which the routers themselves are a part of the wireless node and form a self-configuring network of wireless links. In the mobile router based system, the routers are free to randomly move, leave and enter the system. Therefore, the mobile router based system links can change rapidly in both number and relative position. The links connecting nodes in a network is called a topology of the network. In an infrastructure-based system, a source wireless node communicates via a wireless link with a fixed router which in turn communicates within the infrastructure and further communicates via another wireless link to a destination wireless node. The source and destination wireless nodes communicate primarily through the fixed network topology. A mobile ad-hoc network (MANET) communicates primarily between wireless nodes, without a need for fixed routers. The topology of the MANET is self-configuring with the nodes themselves providing the routing function. The MANET does not require connection to a fixed router, but may be connected to a number of wireless networks (such as a cellular network) or to a number of data networks (such as the Internet).
The evolution and expansion of the Internet and networking has necessitated the expansion of internet protocols from IPv4 (having 4.3×109 addresses) to the most recent IPv6 (having 3.4×1038 addresses). This expansion in Internet protocols has increased the overhead necessary to implement current MANETs since by their original design they communicated at the Internet Protocol (IP) layer. One embodiment of the present invention addresses a fundamental limitation of the original and more recent MANET architectures.
The routing protocols for MANETs fall into one of several groups including pro-active (which is table driven and maintains a list of destination nodes and routes), reactive (which finds a route only when needed), hybrid (which is a mixture of pro-active and reactive), hierarchical, geographical, power aware (due to the fact that power required to transmit a message varies as a square of the distance), multicast, and geographical multicast. Within each group there are multiple protocols, therefore the number of possible protocols available for use is extensive. A common type of MANET routing is reactive routing so, for illustration purposes only, that will be the routing topology utilized to describe the present invention. One node communicating with its next closest neighbor is referred to as local link, peer-to-peer, or single hop communication.
Network communication is primarily based on a model referred to as Open System Interconnection (OSI), which has seven layers of functions, with each layer using only the functions of the layers below and exporting functions only to the layer above. The seven layers are the physical layer, the data link layer, the network layer, the transport layer, the session layer, the presentation layer and the application layer. Computational overhead increases with each successive layer. The layers that are most directly related to this invention are the data link layer (layer 2) and the network layer (layer 3). The data link layer provides an ability to transfer data between network nodes and the addressing in the data link layer is physical and is referred to as Media Access Control (MAC). The network layer provides a function of transferring variable length data sequences between a source node and a destination node and provides network routing, flow control and segmentation and de-segmentation of the data. Currently, routers typically operate in the network layer.